This invention relates generally to sealless pumps and more particularly to a means of detecting corrosion of the sealless pump containment shell.
A sealless pump is a type of centrifugal pump that has its impeller and bearing system isolated from the impeller driving mechanism by an isolating wall or shell that seals the pumping mechanism from the surrounding environment and eliminates the necessity to use rotary seals to seal the pumped fluid against leaking along the shaft. This type of pump is particularly desirable when pumping environmentally sensitive fluids such as hydrocarbons. In one type of sealless pump, the driving mechanism is coupled to the pump impeller by an arrangement of magnets located on the opposite sides of the isolating wall which magnetically connects the torque of the driving mechanism to the impeller. In another type of sealless pump, a canned pump, an electric motor is enclosed within the isolating wall or shell.
The containment shell of a sealless pump has a relatively thin wall, 0.015 to 0.060 inches, depending upon the design. This is typical of both canned and magnetically coupled sealless pumps. Due to the construction of either type of design, it is difficult to determine the rate of corrosion that may be occurring in this shell. Most detection systems currently used, detect leakage through the shell after corrosion has penetrated the shell. Because of the fluids typically pumped with sealless pumps, it is important to have advance warning of shell failure or leakage due to corrosion.
The foregoing illustrates limitations known to exist in present sealless pumps. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.